1. Field of the Invention
The present invention relates to a static discharge device and, more particularly, to a static discharge device for electrically non-conductive fluids.
2. Background of the Prior Art
Whenever an electrically non-conductive fluid flows in physical contact with another surface, a charge is generated in the liquid. Charge generation is especially prevalent in non-conductive fluid flows that include hydrocarbons. The more common charge generating hydrocarbons are gasoline, diesel fuel and jet fuels; however; lubricating oils can also develop a static charge via a filter utilized to clean the oil. Although a complete explanation has not been presented for the charging mechanics, it has been generally accepted that impurities present in the non-conductive fluids, especially hydrocarbons, are the cause for the static charge build-up in the fluid.
When an electrically non-conductive fluid is at rest, impurities are adsorbed along the interface between the fluid fuel and the walls containing the fluid. The impurities attach themselves to the container wall such that all negative or all positive portions of the impurities are adjacent to the wall. In FIG. 1, a container having negative portions of the impurity attach to the wall is disclosed.
The net effect of this at rest alignment is no charge buildup on the fluid. However, when the fluid begins to flow, the positive charges are swept away while the negative charges drain to ground. This results in a net positive charge to the fuel flow (see FIG. 2) in the direction of the arrow.
Had the positive portions of the impurities attached to the container wall, the result would have been a net negative charge to the fuel flow in the direction of the arrow with the positive charge draining to ground.
The impurities discussed above can be quantified in a parts per million or parts per billion context. However, depending upon the size of the container (pipe), the velocity of flow and the type of fluid, along with the quantity of the impurities, the ultimate developed charge can rise to magnitudes well beyond 1000 volts.
The static charge buildup and high voltage levels developed when an electrically non-conductive fluid fuel such as gasoline is being pumped, causes problems pertaining both to safety and performance. Safety is compromised when the charged gasoline is transported to a partially filled storage tank having a vapor portion therein that falls within an explosion range. The charged gasoline can generate a high energy spark to ground that is capable of causing an explosion with catastrophic results.
The performance of a charged fluid fuel such as gasoline is denegrated due to the inefficient mixing of the air and gas molecules within a burning chamber. More specifically, when utilizing gasoline in an internal combustion engine, air and gas are injected or mixed in a piston cylinder to provide an explosive combination that is utilized to develop power. When the gasoline has a static charge thereupon when injected into a piston cylinder, a portion of the gas does not mix with air. Instead, the "unmixed" portion becomes attracted to the grounded internal metal walls of the cylinder as well as the cylinder heads and pistons. The unmixed portion does not generate power but still burns thereby generating numerous pollutants such as hydrocarbons, carbon monoxides and nitrous oxides, or becoming a carbon deposit on the pistons, cylinder heads and/or valves.
One method to decrease the static charge buildup on hydrocarbon fluids, thereby decreasing explosions and pollution, is to install a static discharge device in the line supplying the fluid at the entrance port of a storage tank, or adjacent to an internal combustion engine that receives the fluid. The static discharge device is capable of directing the static charge from the hydrocarbon fluid safely to ground thereby providing a neutral or uncharged fluid into a receiving member.
Prior art static discharge devices for hydrocarbon fluids utilize projecting conductive rods attached to grounded inside walls of a storage tank to minimize spark and discharge the surface of the fluid to ground.
The problem with this static discharge system is that it allows a charged fluid to enter the tank instead of removing the static charge from the fluid before the fluid enters the tank.
A need exists in the art for a device that removes a static charge from a hydrocarbon fluid before the fluid enters a storage facility thereby removing the chance for sparks and explosions.
Also, a need exists in the art for a device that removes a static charge from a hydrocarbon fluid before the fluid is combined with air to generate an explosive mixture. Removing the static charge imports a more complete burn to the fluid with corresponding reductions in hydrocarbon particulate matter, carbon monoxide and nitrous oxide emissions. The device should also be relatively inexpensive to manufacture.